Lecture 24-Global Warming

Lecture 24-Global Warming - Sharing Amboseli National Park...

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Unformatted text preview: Sharing Amboseli National Park 2006 KAREL PRINSLOO / AP 1 Solutions :Soil Conservation Conventional-tillage Conservation tillage Cropping methods Windbreaks Land Classification 2 Soil Restoration Natural fertilizers Compost Manure Commercial inorganic fertilizers Crop rotation 3 Tragedy of the Commons Garrett Hardin Science , 162(1968): 1243-1248 4 Tragedy of the Commons Imagine a pasture open to all Each farmer will keep as many animals as possible Works as long as numbers of farmers and animals are below carrying capacity 5 Tragedy of the Commons Add an animal..... Benefit goes to individual Cost is borne by all users 6 Tragedy of the Commons Each farmer concludes the sensible course is to add additional animals All farmers come to same conclusion This cannot last in a world with limits 7 Tragedy of the Commons 8 Tragedy of the Commons Freedom in a commons brings ruin to all 9 Tragedy of the Commons Most oceans, forests, and range lands are or have been commons 10 Tragedy of the Commons Before exploitation, most populations settle around carrying capacity Exploitation reduces competition; increases net recruitment to population per unit time 11 Tragedy of the Commons Freedom in a commons brings ruin to all 12 Tragedy of the Commons Most oceans, forests, and range lands are or have been commons 13 Tragedy of the Commons Before exploitation, most populations settle around carrying capacity Exploitation reduces competition; increases net recruitment to population per unit time 14 MSY Net Recruitment Population Size 15 Maximum Sustainable Yield (MSY) How many individuals can be removed from population indefinitely How many can be removed without depleting population 16 Maximum Sustainable Yield (MSY) Problems: Treats population as homogenous (age, size, growth rates) Treats environment as constant Reliable MSY estimates are difficult to determine 17 Maximum Sustainable Yield (MSY) Problems: Maximum sustainable yield is only one way to harvest population 18 Maximum Sustainable Yield (MSY) Fixed-Quota MSY: Same amount is removed from population each year Harvest can exceed recruitment if population fluctuates 19 Maximum Sustainable Yield (MSY) Can lead to a death spiral for the population 20 Maximum Sustainable Yield (MSY) Density (Population Size) R e c r u i t m e n t o r H a r v e s t i n g R a t e N m H m H h H h = High quota H m = MSY quota 21 Maximum Sustainable Yield (MSY) Fixed-Effort MSY: Constant harvesting effort within a time period (season) 22 Maximum Sustainable Yield (MSY) Fixed-Effort MSY: Lower risk of driving population to extinction Yield varies with population size (good and bad years) 23 Maximum Sustainable Yield (MSY) Fixed-Effort MSY: Requires rigorous enforcement to make sure effort is equal 24 Density (Population Size) R e c...
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This note was uploaded on 08/30/2008 for the course BIOS 230 taught by Professor Gibbons during the Spring '08 term at Ill. Chicago.

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Lecture 24-Global Warming - Sharing Amboseli National Park...

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